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12.09: Weathering steel – 30 years of experience in Banedanmark
Author(s) -
Holmstrøm Peter,
Nielsen Mogens G.,
Cero Dritan
Publication year - 2017
Publication title -
ce/papers
Language(s) - English
Resource type - Journals
ISSN - 2509-7075
DOI - 10.1002/cepa.409
Subject(s) - weathering , weathering steel , corrosion , service life , engineering , test (biology) , forensic engineering , civil engineering , geology , metallurgy , mechanical engineering , materials science , paleontology , geomorphology
ABSTRACT Banedanmark has used weathering steel for more than 30 years and has gathered unique information about corrosion of weathering steel during this period. Not only has the corrosion rates been noted – but also the good and poor detailing. The conclusions of this will be given in this paper. Based on the information gathered from the tests, a method for estimating the corrosion lifetime for the specific type of structure is given. Since 1986 weathering steel has been widely used on the Danish rail network for overhead line equipment structures such as masts and frames etc. As these structures now represent a very large investment to the owner of the rail net, it is crucial to follow if the expected lifetime from design is valid. These structures are based on a ‘standard‐design’ developed by Ramboll in the mid 80ti'es. At that time the knowledge on how weathering steel would behave on these specific structures was limited, hence a test‐programme was carried out from 1988 to 1994, in order to verify the corrosion rate in general, along with the suitability of the design philosophy of details. This test‐programme was carried out using designated test‐masts that was located along the rail track at selected locations. After seven years of studying the test‐masts, the test‐programme was stopped, as these results indicated that the required service life would be met. And there was not observed any critical items on the detailing used. Now, after almost 30 years of service, the designated test‐masts are still available, and as results from the first test‐regime indicated some conservatism in design assumptions, it might be the case that the existing structures can be considered safe beyond the original design life of 50 years. To investigate this further a pilot test‐has been carried out, to check if the test‐regime is still suitable for gathering new information after almost 30 years of exposure. This initial test showed that it might be possible to increase the expected service life from 50 to perhaps 80–100 years of existing structures. In addition it was evident that the design philosophies of details are suitable for long time exposure. It even indicated some conservatism in the philosophy of detailing too. The tests have gathered unique knowledge of how mast structures for overhead lines of weathering steel behaves after long time exposure.